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Participants: Prof John A Endler (PI), Andy T D Bennett
Aims and background: The vast variation among bird species in colouration is well known, but there are almost no studies of its causes except for studies of sexual selection, where single aspects of the colour pattern are related to mating success. However birds are constantly at risk from predation, suggesting that avoiding predation may be an important function of plumage colour patterns. This has not been investigated seriously using modern comparative phylogenetic methods combined with the latest information on bird vision. This project will attempt to predict the colour, sizes, shapes, and luminances of the cryptic (difficult to detect) colour patterns of Australian honeyeaters directly from their microhabitat use, which enables us to estimate the visual background parameters. Parameter matching is a prerequisite for reducing detection by predators. This well-defined monophyletic family (Meliphagidae) is large enough for comparative studies, and also large enough for both within- and among-habitat comparisons as most habitats have many sympatric, although not necessarily syntopic, species.
Scientific significance and innovation: Avoiding detection by predators is essential in understanding almost all aspects of a species' biology because it has strong ecological and evolutionary implications. Heretofore there have been no phylogenetic studies of crypsis in any animal group. Moreover there have not been any studies combining estimates of visual contrast via visual physiology and phylogenetic analysis. There have been visual ecology studies of individual species relative to sexual selection and studies of colouration in a purely phylogenetic context, but this will be the first to combine the methods. Honeyeaters are excellent because there are so many species and they are common and easy to observe. This study will combine methods, concepts and mathematical modelling from phylogenetics, comparative biology, visual physiology, visual ecology, avian biology, animal behaviour, behavioural ecology and evolutionary biology.
Potential national benefit and strategic alignment with the aims of the CIE: This project falls under the National Research Priority of "An Environmentally Sustainable Australia" and within that the priority goal "Responding to climate change and variability and Sustainable use of Australia's biodiversity." Understanding the causes of diversity of colour patterns, which influence so many aspects of an individual's life (survival and reproduction) also helps us to understand the generation and maintenance of biodiversity. Climatic change causes predictable changes in the proportions of some microhabitats and affects all habitats' visual appearance, generating predictable changes in fitness related to colour patterns. Thus we may be able to make predictions about which species are most likely to be at risk given their microhabitat preferences and colour pattern parameters. The putative integrative nature of this project is central to the aims of the CIE, combining ecology, evolution, and physiology.